+
+#if defined DEBUG && DEBUG > 1
+/* Print list of in-core pages of a the current rrd_file. */
+static
+void mincore_print(
+ rrd_file_t *rrd_file,
+ char *mark)
+{
+#ifdef HAVE_MMAP
+ /* pretty print blocks in core */
+ off_t off;
+ unsigned char *vec;
+ ssize_t _page_size = sysconf(_SC_PAGESIZE);
+
+ off = rrd_file->file_len +
+ ((rrd_file->file_len + _page_size - 1) / _page_size);
+ vec = malloc(off);
+ if (vec != NULL) {
+ memset(vec, 0, off);
+ if (mincore(rrd_file->file_start, rrd_file->file_len, vec) == 0) {
+ int prev;
+ unsigned is_in = 0, was_in = 0;
+
+ for (off = 0, prev = 0; off < rrd_file->file_len; ++off) {
+ is_in = vec[off] & 1; /* if lsb set then is core resident */
+ if (off == 0)
+ was_in = is_in;
+ if (was_in != is_in) {
+ fprintf(stderr, "%s: %sin core: %p len %ld\n", mark,
+ was_in ? "" : "not ", vec + prev, off - prev);
+ was_in = is_in;
+ prev = off;
+ }
+ }
+ fprintf(stderr,
+ "%s: %sin core: %p len %ld\n", mark,
+ was_in ? "" : "not ", vec + prev, off - prev);
+ } else
+ fprintf(stderr, "mincore: %s", rrd_strerror(errno));
+ }
+#else
+ fprintf(stderr, "sorry mincore only works with mmap");
+#endif
+}
+#endif /* defined DEBUG && DEBUG > 1 */
+
+
+/* drop cache except for the header and the active pages */
+void rrd_dontneed(
+ rrd_file_t *rrd_file,
+ rrd_t *rrd)
+{
+ unsigned long dontneed_start;
+ unsigned long rra_start;
+ unsigned long active_block;
+ unsigned long i;
+ ssize_t _page_size = sysconf(_SC_PAGESIZE);
+
+#if defined DEBUG && DEBUG > 1
+ mincore_print(rrd_file, "before");
+#endif
+
+ /* ignoring errors from RRDs that are smaller then the file_len+rounding */
+ rra_start = rrd_file->header_len;
+ dontneed_start = PAGE_START(rra_start) + _page_size;
+ for (i = 0; i < rrd->stat_head->rra_cnt; ++i) {
+ active_block =
+ PAGE_START(rra_start
+ + rrd->rra_ptr[i].cur_row
+ * rrd->stat_head->ds_cnt * sizeof(rrd_value_t));
+ if (active_block > dontneed_start) {
+#ifdef USE_MADVISE
+ madvise(rrd_file->file_start + dontneed_start,
+ active_block - dontneed_start - 1, MADV_DONTNEED);
+#endif
+/* in linux at least only fadvise DONTNEED seems to purge pages from cache */
+#ifdef HAVE_POSIX_FADVISE
+ posix_fadvise(rrd_file->fd, dontneed_start,
+ active_block - dontneed_start - 1,
+ POSIX_FADV_DONTNEED);
+#endif
+ }
+ dontneed_start = active_block;
+ /* do not release 'hot' block if update for this RAA will occur
+ * within 10 minutes */
+ if (rrd->stat_head->pdp_step * rrd->rra_def[i].pdp_cnt -
+ rrd->live_head->last_up % (rrd->stat_head->pdp_step *
+ rrd->rra_def[i].pdp_cnt) < 10 * 60) {
+ dontneed_start += _page_size;
+ }
+ rra_start +=
+ rrd->rra_def[i].row_cnt * rrd->stat_head->ds_cnt *
+ sizeof(rrd_value_t);
+ }
+#ifdef USE_MADVISE
+ madvise(rrd_file->file_start + dontneed_start,
+ rrd_file->file_len - dontneed_start, MADV_DONTNEED);
+#endif
+#ifdef HAVE_POSIX_FADVISE
+ posix_fadvise(rrd_file->fd, dontneed_start,
+ rrd_file->file_len - dontneed_start, POSIX_FADV_DONTNEED);
+#endif
+#if defined DEBUG && DEBUG > 1
+ mincore_print(rrd_file, "after");
+#endif
+}
+